This invention relates to the use of polymeric compositions for roofing and the like. More specifically, it relates to the use of such compositions containing polyurethane foams.
It is known to use polyurethane foam layers on roofs, walls, and the like, to protect against weather and provide insulation, among other things. One method of applying such foams involves spraying precursor reactants for polyurethanes directly onto wooden, metallic, or other roof substrates, and allowing the precursors to react in place to form a rigid foam layer. The layer is then painted, or otherwise coated, with a thin protective layer of paint to protect the polyurethane foam against damage, for example, from the weather.
Difficulties have been encountered using prior compositions and techniques, in that the resulting painted polyurethanes are soft and are easily damaged, for example, by workers walking on the roofs, by hail storms, or by the eventual wearing away or cracking of the protective paint layer.
To overcome some of these problems, attempts have been made to make sturdy polyurethane foams having densities sufficiently high to give structural rigidity to the foam sufficient to resist the expected abuse typically encountered. However, these attempts have been largely unsuccessful, because the polyurethane foam roofs with paint coatings have still been insufficiently sturdy for many uses, lack durability, require large amounts of reactants to form the high density foams, and are expensive not only in raw materials, but also in the amount of labor required to apply the materials to a roofing substrate. Also, the applications are often unduly time-consuming.
These and other problems of the prior art compositions and techniques can be overcome, or greatly alleviated, in accordance with the present invention.